The present invention relates to a suspension for an assembly generating, absorbing, and/or transmitting torque in the drive train of a motor vehicle. In particular, the invention relates to a suspension of an electric motor between the engine block of a combustion engine and the transmission housing of a downstream manual or automatic transmission. The electric motor then optionally serves as a starter of the combustion engine, as a charging generator for the automobile battery, as a torsional-vibration absorber of the combustion engine, or, with the combustion engine shut down, as an electric drive. This concept has been explained under differently weighting the individual aspects in a number of patent applications (e.g. DE 33 06 481, DE 44 06 482, DE 44 47 537, DE 44 47 574, DE 195 32 135, DE 195 32 128, DE 195 32 136, DE 195 32 163, DE 195 49 259, DE 195 32 164, DE 32 129 filed by Clouth Gummiwerke AG, Cologne, Germany).
Therein, the drive arrangement is generally designed in such a manner that the combustion engine and the electric motor act on a common output shaft which leads to a manual or automatic transmission.
In the state of the art, arrangements are known (see e.g. DE 32 20 950 C2) where a stator back of the electric motor (with a stator, a stator winding, and a rotor which can be coupled secured against rotation onto the output shaft of the combustion engine) is screwed via a stator carrier between an output flange of the combustion engine and a housing of the transmission. Thereby, no force-related decoupling takes place between the stator back and the clamping of the stator carrier between the engine block/transmission housing.
The situation, however, that modern vehicles have transmission housings as well as engines blocks of the combustion engine, which consist of aluminium alloys, while electric motors (in particular the stator) have a very high proportion of iron, gives rise to considerable problems. The thermal expansion coefficient of aluminium is approximately twice that of iron. In addition, considerable temperature differences occur between the electric motor and the combustion engine, depending on the mode of operation. The temperature variations, too, to which such a drive unit of a motor vehicle is subjected due to the operating temperature and the ambient conditions are in the range from approx. xe2x88x9250xc2x0 C. to approx. +200xc2x0 C.
The different thermal expansion coefficients of the two materials and the temperature variations cause expansions/contractions, which may influence the stator of the electric motor (changes of the air gap, getting out of roundness, etc.) and/or the combustion engine/transmission unit (deformation of flanges, stress cracks, jamming of pistons, etc.).
Starting from these assumptions the invention is based on the object to provide a suspension for an assembly generating, absorbing, and/or transmitting torque in the drive train of a motor vehicle, in which the above mentioned problems do not occur.
In order to eliminate this problem the following inventive solution is proposed: a suspension for an assembly generating, absorbing, and/or transmitting torque in the drive train of a motor vehicle with a combustion engine, with a first non-rotating part of the assembly being connected with the engine block via a coupling element in a manner so as to be essentially secured against rotation, and a second rotating part of the assembly being connected with an output shaft protruding from the engine block, and with the first and the second part being designed so as to encompass the output shaft at least partially, characterised in that the assembly comprises materials with a thermal expansion coefficient different from that of the material of the engine block of the combustion engine, and the coupling element is highly resilient in the radial direction so that it is readily deformed under thermal expansion/contraction.
With this configuration of the suspension, reactions of the expansion of the first non-rotating part on the attachment at the engine block are virtually completely eliminated in a space saving and stable manner. The rigidity of the arrangement in the corresponding directions or degrees of freedom, respectively, can be established according to the requirements, in that the material properties and dimensions or resilience, respectively, are appropriately dimensioned.
In the following, several developments and particularly advantageous configurations or embodiments, respectively, of this inventive principle will be explained.
The invention can be employed particularly effectively if the assembly is an electric motor, preferably an asynchronous motor, with the first non-rotating part being the stator and the second rotating part being the rotor of the electric motor.
In a first embodiment of the invention the coupling element is a disk which extends in an essentially radial direction, at which at least one flange is formed oriented essentially coaxially with the output shaft, which can be deformed in the radial direction, with the disk being connected with the engine block and the flange being connected with the stator. In this manner an arrangement can be realised which is highly rigid against deformation in the axial direction (parallel to the output axis) because the radial dimensions of the disk are to be as small as possible in any case. The same applies for the area of the disk in the radial direction. The flange which at its output end is essentially coaxially oriented and with its free end is connected with the stator allows an expansion/contraction of the stator relative to the engine block due to temperature effects or differences and to the different thermal expansion coefficients. In this context, the rigidity or resilience of the suspension in the radial direction can be established as a function of the choice of material and the dimensioning of the flange.
In a particularly preferred embodiment of the inventive suspension at least one radially oriented web which is arranged at least along a portion of the circumference of the flange is formed at the end of each flange, which is remote from the disk, which connects the flange with the first non-rotating part of the assembly.
In addition, it is possible that the outer surface of the first non-rotating part of the assembly, the or each flange and the webs define an annular space through which a cooling fluid can flow.
Alternatively, in a preferred embodiment of the invention the disk is formed by two annular joined sheet metal parts at whose radially inner edges a (co-)axially oriented flange each is formed, with a radially oriented web being formed at the edge of same which is remote from the disk.
In another embodiment of the invention the flange is integrally connected with the first non-rotating part of the assembly with the end of same which is remote from the disk. In the case of the electric motor, the non-rotating part of the assembly, for example, is the stator back ring.
In another embodiment of the invention a radially oriented collar is arranged at the outer circumference of the first non-rotating part, which comprises several elongated holes along its circumference, adjacent to which fastening holes are arranged further radially outward, and webs which are resilient in the radial direction are formed further radially inward.
Additional properties, characteristics, advantages, and modifications will become apparent from the following description of the drawing in which embodiments of the invention are illustrated.